This invention relates to the field of construction and maintenance of railroad road beds, and particularly to a method for producing usable sleepers or crossties, at economically justifiable cost, from materials usually of value to railroads only as salvage, and also to the compound crossties so produced.
A crosstie is a structural member of the roadbed to the top surface of which rails are secured extending along the roadbed. It is placed upon or embedded in the aggregate ballast to maintain the guage or spacing between the rails and the alignment of the rails, and to distribute the bearing load to the ballast.
Historically, crossties have been produced in this country by sawing or hewing logs of proper length into various sizes ranging in cross section from 5".times.5" to 10".times.12", and in length from 8 feet, for right-of-way use, to 12 feet, for use at switch turnouts, bridges, etc. Although more expensive, oak is the preferred material for crossties, but other woods are also usable.
After a period of use, crossties become weak, due to deterioration from mechanical wear at the points where the rail is affixed, to longitudinal checking or mechanical failure of the wood, or to attack from biological organisms, so that the crossties can no longer perform their functions, and must be replaced.
Replacement of crossties was first accomplished by pulling the spikes holding the rails to the wood and laterally pulling the entire tie from under the rail, to be replaced with a new tie, after which elevation, alignment, and gauge were reestablished.
This replacement method, accomplished basically by manual labor, resulted in an accumulation of old ties which, although no longer useful for their intended purpose, were still useful as fence posts, for landscape cribbing, etc., and thus had some salvage value.
As labor became more expensive and mechanical technology improved, new track maintenance machines were developed to accomplish removal and replacement of crossties more efficiently and productively. To minimize the amount of readjustment to elevation, alignment, and gauge, it was found to be more efficient to cut the ties into three pieces, while still in place in the roadbed, by means of vertically oscillating saw blades positioned just within the rails, thus producing three pieces of wood. The center section is referred to as the center butt, and the outer sections are referred to as field ends. These sections are too short to have even the salvage value referred to above for entire used crossties, and disposition of these pieces along the right-of-way, as by burning or burial, has disadvantages and in some areas has been prohibited, so it has become necessary to pick up these butts and ends after removal from the roadbed and transfer them, at significant cost, for disposition at suitable landfill areas usually some distance from their site of removal.
Currently, about 26 million crossties are removed annually in the United States, at an average of 32 board feet per crosstie--which represents 832 million board feet of tie material, calling for about 1.4 billion board feet of standing timber. A principal objective of this invention is to reduce so great a demand for standing timbers to be made into crossties.
In the railroad industry, it is the practice to scrap rolling stock when by damage or age it can no longer economically justify repairs. Regularly, steel plate is salvaged from car sides, and brake pipe material and brake rod material is also salvaged, presently for recycling back into steel.
The present invention contemplates constructing usable compound crossties from the scrap steel plate, rod, and pipe just described and the center butts from tie replacement operations. Field ends are generally unusable for the purpose of this invention, but about half the center butts are so usable, two being needed for one complete compound tie.